Vehicles, equipment or machinery may use electric motors that are controlled by inverters or motor controllers. A prior art sensor may measure current in one or more input conductors, such as wires or cables, that feed an electric motor from the inverter. More generally, a prior art sensor may measure current in one or more conductors associated with any power electronics device that uses power semiconductors, such as insulated gate, bipolar transistors (IGBT) or metal-oxide semiconductor field-effect transistors (MOSFET).
Certain prior art sensors for sensing current in a conductor associated with an electric motor may fail prematurely because they have poor resistance to thermal stress. In some prior art sensors, self-heating of a ferromagnetic core, from induced eddy currents and hysteresis losses, can promote failure of a thermally sensitive device, such as Hall effect magnetic field sensor embedded within core, or an inductive coil used with the core. Other prior art sensors for sensing current in the conductor may occupy a larger than desired volume because the maximum circuit density can be limited, while effectively addressing thermal stress. Still other prior art sensors may not respond appropriately for rapid changes in current; hence, fail to respond for a sudden short circuit at an inverter output. Thus, there is a need for a compact sensor for sensing current that is resistant to failures or reduced longevity associated with thermal stresses or associated with inaccurate sensing of rapid changes in current.